Extraordinarily gratifying results have been obtained with enzyme replacement therapy in patients with Gaucher's disease. All patients who received macrophage-targeted human placental glucocerebrosidase had significant clinical benefit. The hemoglobin level rose in all patients, and within six months from the initiation of therapy, the size of the spleens had decreased in all recipients. The enzyme injections were well tolerated and none of the patients became sensitized to the preparation. Patients who received the enzyme were able to resume activities such as work or school that they had been unable to carryout before enzyme replacement. Based on their findings, the U.S. Food and Drug Administration has approved the use of macrophage-targeted glucocerebrosidase as specific therapy for patients with Type 1 Gaucher's disease.